1. Field of the Invention
The present invention relates to automated material handling devices, and more particularly to an automated, multi-belt distribution head reciprocating stacker for sheet, strip material.
2. Description of the Related Art
Rubber is often manufactured in the form of a thin and narrow sheet of material. The thin, narrow rubber sheets are commonly produced in a continuous manner resulting in an extremely long sheet of rubber. It is not possible to store, package or transport the rubber in long flat sheets, so the rubber is commonly folded into a multilayer pile and stacked on a pallet for storage and shipping. The rubber sheet may be folded and stacked onto the pallets by hand, but this is an inefficient process. Many devices are used to automate the process of folding the rubber sheets. These stacking and folding devices commonly comprise an assembly of conveyor belts and distribution heads to evenly stack the rubber sheets onto manageable piles. A network of computers that are programmed for the specific process controls the assembly.
Specific examples of automated sheet material stackers that are illustrative of the present industry are discussed in the following patent documents.
U.S. Pat. No. 3,913,904 to Occhetti discloses a stacking machine for rubber sheet material. The patent discloses an assembly for automatically converting a continuous delivery of sheet material into a horizontally reciprocating motion for creating a uniform stack of sheet material. The reciprocating mechanism includes a cut-off device so that discrete sheets are created to a precise length and so that all cut sheets are stacked vertically. The Occhetti device provides for the stacking of relatively wide sheet material that is about equal in width to the size of the pallet.
U.S. Pat. No. 6,155,551 to Russ et al. discloses a reciprocating stacker for stacking a relatively thin, flexible and continuous sheet of material evenly onto a pallet The stacker includes a distribution head, which receives the sheet material from a conveyor belt and distributes it onto a pallet. The head reciprocates in a first direction to lay the material out in a zigzag while simultaneously translating in a second direction normal to the first direction to distribute the material evenly laterally across the surface. The feeder head comprises a set of rollers driven by means of a rack and pinion gear arrangement. This feeder head requires the movement of the carriage in order to provide a driving force for the rollers and thus dispense the sheet material.
U.S. Pat. No. 4,507,109 to Meschi discloses an apparatus for reception and transfer of sheet material. The apparatus is adapted to receive printer sheets and form the long printer sheets into evenly distributed stacks. The apparatus includes a guiding means, a control operated cutting means, and a supporting and piling means.
U.S. Pat. No. 5,064,179 to Martin discloses a method of forming zigzag shaped piles from a continuous band of a flexible material and a machine for carrying out the method. The band of material is deposited and folded onto a support, and at the end of the formation of a pile the band is ruptured along a predetermined folding line, the forward movement of the band is stopped and the pile is removed. This method is discussed for use in high speed printers.
There are many different types of rubber that are formed in long sheets that must be handled by the stacking assemblies discussed above. Many problems exist with the existing stacking assemblies due to the fact that there are varying types of rubber produced. Different types of rubber stock react differently due to the plasticity and tensile characteristics of the rubber. When referring to plasticity, the reference is to the degree to which a material is capable of being permanently deformed. When referring to tensile, the reference is to a measure of the strength of a material, and more particularly to the maximum tolerable load per unit of original area. Many of the existing stacking assemblies require mechanical adjustments when different types of rubber are used.
Another problem is that when rubber is produced the thickness of the stock sheet is not always uniform. The existing stacking assemblies commonly have a low tolerance for variable stock thickness. If the distance between the assembly's rollers is not wide enough for the stock to pass through, the distance must be adjusted by loosening the fasteners holding the rollers in place. Another problem is that, due to variable stock thickness, it is sometimes necessary to vary the speed of the stock that is distributed onto the stack. It is advantageous to be able to distribute more or less material to enable the stacker to maintain a uniform stack.
Therefore, there is a need for an automated reciprocal stacking assembly that is capable of handling and distributing a continuous sheet of material into a stack of a predetermined height onto a pallet for storing and shipping. It is also desirable to have an automated reciprocal stacking assembly that provides an increased opening to allow for a much wider entrance for the rubber stock for automated loading of the stock material. Another need is for an automated reciprocal stacking assembly that provides a set of distribution belts that are held together by a tensioning device that allows the assembly to accommodate a large variation in stock sheet thickness. It is further desirable to have an automated reciprocal stacking assembly that is capable of varying the stock distribution speed across the linear plane of motion, allowing the amount of stock material to be varied to maintain a uniform stack of rubber. A further benefit would be provided by an automated reciprocal stacking assembly that provides a computer control program that may be altered to consider the plasticity, rebound and tensile properties of varying rubber stocks.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus an automated reciprocal stacking assembly solving the aforementioned problems is desired.